Known nacelles of wind power turbines define a compartment housing many of the control and actuating devices of the wind power turbine. The blade assembly comprises a hub; and a number of blades adjustable with respect to the hub about their longitudinal axes, to adjust the pitch of the blades. The nacelle also houses the blade pitch adjustment actuating and control devices. The nacelle of some known wind power turbines is also designed to house frequency converters and transformers. Modern wind power turbines have pylons ranging between 60 meters (196.85 feet) and 120 meters (393.7 feet) in height. So, to carry out the necessary maintenance of the actuating and control devices, the mechanical parts of the nacelle, and the instruments inside it, easy access by maintenance workers to the inside of the nacelle is of vital importance. At present, wind power turbines are normally equipped with service ladders inside the pylon, and with a winch inside the wind power turbine for hoisting heavy, bulky material; and small parts are sometimes carried by workers in backpacks.
Climbing up and down ladders, possibly several times a shift and carrying backpacks, is very tiring, uneconomical, and at times even dangerous.
For this reason, many known wind power turbines are equipped with a lift, housed inside the pylon and movable along a first axis, for carrying two or three workers, tools, instruments, and medium-sized spare parts, and which connects the bottom end of the pylon to a panoramic platform fixed to the pylon, beneath the nacelle, and of the type described in U.S. Pat. No. 6,998,729 B1.
Known lifts, however, stop well below the nacelle, which means the last part of the ascent to the nacelle must be made by ladder, with all the drawbacks referred to above.
The reason the lift stops short of the top of the pylon is because of the cable bundle, which is normally wound into a ring underneath the nacelle, to allow the nacelle to rotate with respect to the pylon without stressing the cables. And since the nacelle is normally designed to make two and a half turns with respect to the pylon, the ring formed by the cable bundle underneath the nacelle is relatively large and normally hinders access to the nacelle.